1. Field of Invention
This invention relates to methods and apparatus for protecting eyes from light radiation, particularly in connection with, but not limited to, medical procedures.
2. Description of Related Art
Various medical procedures involve the generation of bright and/or intense light from which human eyes must be shielded in order to avoid retinal damage, temporary vision loss from visual overload, and/or headaches or nausea that can result from prolonged exposure to such light. Various procedures are now being performed, are under development, or will be developed that use laser light or high intensity pulses of diffuse light. Examples of such medical procedures include hair removal procedures, tattoo removal procedures, skin regeneration procedures and dental procedures.
In recent years, auto-darkening technology has been used in the welding industry. Such auto-darkening technology may include an optical sensor and a liquid crystal panel that is switchable between a “see-through” or “light” state, in which a wearer can see clearly through the panel in normal ambient light conditions, and a “darkened” state, in which only a small amount of light passes through to allow the wearer safely to view a source of very bright and/or intense light such as the light emitted during an arc welding process. The liquid crystal panel enters the “darkened” state when the optical sensor detects a flash of intense light.
In medical procedures, the doctor or technician performing the procedure typically uses passive dark eyewear to protect his or her eyes from a laser light source or high intensity diffuse light source. Thus, the doctor or technician typically views the target, puts on the passive dark eyewear, irradiates the target with the light source, takes off the eyewear, and then views the effect of the irradiation.
U.S. Pat. No. 5,877,825 to Kotler discusses certain disadvantages of safety glasses that block only a specific wavelength of pulsed laser radiation used in industrial, medical and scientific applications, and discloses safety glasses in which an electro-optic shutter is provided which, when applied with a voltage signal, switches from a transparent state to an opaque state within a response time. A voltage signal is applied at an operational time interval that is slightly longer than the response time so that, by the time of emission of each radiation pulse, the electro-optic shutter is in the opaque state. Kotler discloses that an IR transmitter and detector may be used for a wireless connection between the safety glasses and a laser.
U.S. Pat. No. 6,170,947 to Colles et al. discloses a system for protection from light generated by interaction of laser energy with matter, for use in medical applications and particularly in dental applications. The light protection system includes one or more optical elements that are placed in an active, i.e., light blocking, state in response to an electrical signal. This signal initiates optical element activation approximately one millisecond before firing of a lasing apparatus, which is the approximate time for the one or more optical elements to transform from an inactive state to the active state.
Neither the Kotler patent nor the Colles patent discloses a system for protecting against intense diffuse light in a medical procedure.